Aviation fuel



Patented Nov. 26, 1946 umrm STATE AVIATION FUEL Thomas B. McCulloch, Baytown, Tex., assignor to I Standard Oil Development Company, a corporation of Delaware I No Drawing. Application J une 310, i944,

' Serial No. 539.783

. Claims.

The present invention is concerned with an improved aviationffuel. More particularly, the

invention relates to a fuel composition comprising spiropentane, which gives-improved performance in the aviation motor.

- The problem of producing a proper fuel for'use in the aviation motor'is one that has attracted a large number. of workers,' due-to the complexity of the requirements for a perfect fuel which will perform equally well under the different conditions encountered in themotor. For example, the fuel requirements of the aviation motor are quite different under cruising conditions from the conditions obtaining when the motor is ac-.

celerating during take-off or--while the airplane is climbing. I

As a solution to the problem of providing a proper aviation fuel suitable for use under the different conditions of operations, it has been proposed that aromatics, naphthenes, isoparaffins, cracked gasoline components, and the like either comprise the major portion of the fuel or be added thereto in substantial amounts. Addition of tetraethyllead and other anti-detonants such as amino toluenes and their homologues has also been proposed; All of these expedients, while improving the various aviation fuel base stocks, provide an improvement in the fuels performance during either cruising conditions or [during take-off" or while the plane is climbing composition, the other constituents of which are predominantly isoparafflnlc in nature. Thus,

besides spiropentane, the fuel may comprise isopentane, isohexaneisoheptane, iso-octane, and the like. The improved fuel of my invention may also include amounts of tetraethyl lead, iron carbonyl and other anti-detonants such as the class of compounds illustrated by the amino toluenes.

'In some instances it may be desirable to prepare a fuel in accordance with the present invention which comprises splropentane and quantities of. the aromatics and/or naphthenes. Mixtures of the latter types of hydrocarbons with isoparaflins form suitable base stocks to which the spiropentane may be added. Y

The isoparaflins may be obtained from naturally occurring sources or may be produced synthetically as by the well known alkylation and/or isomerization reactions. Irrespective of the source of the isoparafiins, it is preferred to employ them in my fuel composition in relatively pure form.

Suitable fractions of crude petroleum from crude oils of the coastal type, which boil in the It is contemplated that the amount of spiropentane comprising the aviation fuel will vary with the type of base stock with which it is blended, but in general will not exceed 50% by volume of the fuel composition. It is contemplated that from 5% to 25% will be employed in s most instances. It may be pointed out that spiropentane boils at a temperature in the neighgasoline boiling range, may also form the base stock of my improved fuel. Generally, the hydrocarbon fractions will not have a boiling point which exceeds 350' F. When using crude petroleum fractions with spiropentane, it may be desirable to employ other blending agents such as alkymers and tetraethyl lead to obtain maximum utilization of the qualities of the admixture. The tetraethyl lead may be employed in most instances, in amounts notexceeding 6 cc. per gallon of fuel. 7

As a specific example of the improved fuel composition, an aviation fuel in accordance. with the present invention may be prepared by adding 20' parts of spiropentane to 80 parts of an alkymerhaving a vapor pressure of 4 pounds Reid. The vapor pressure of this composition is slightly over 6' pounds Reid and is satisfactory for use in an aviation motor. I Y

In another example, a. fuel, in accordance with the present invention, is prepared by blending 25 parts of spiropentane with a mixture composed of equal parts of 2,2, dimethyl butane, commonly called neohexane and iso-octane. This composition is also satisfactory for use as an aviation fuel.

The nature and objects of the present invention having been described and illustrated what I wish to claim as new and useful and to secure by Letters Patents is:

1.' An aviation fuel'comprisins a minor portion of spiropentane and a major portion of hydrocarbons boiling in the gasoline boiling range.

2. An aviation fuel in accordance with claim 1 in which the hydrocarbons boiling in the gasoline boiling range are obtained from crude petroleum.

3. An aviation fuel in accordance with claim 1 in which the hydrocarbons boiling in the gasoline range are produced synthetically.

4.. An aviation fuel in accordance with claim 1 in which the spiropentane comprises approximately 25% by volume of the incl.

5. An aviation fuel comprising a minor amount of spiropentane and a major amount of isoparaffinic hydrocarbons.

4. a 6. An aviation fuel in accordance with claim 5 in which the minor amount of spiropentane comprises approximately 25% by volume of the iuel. '7. An aviation fuel in accordance with claim 1 which comprises tetra'ethyl lead. I I

8. An aviation fuel in accordance with claim 5 which comprises tetraethyl lead.

9. An aviation fuel which comprises spiropencane as a "minor component and a, mixture of isoparaflinic, naphthenic and aromatic hydrocarbons as a major component.

10. An aviation fuel in accordance with claim 9 which comprises tetraethyl lead.

1 THOMAS B. McCULLOCH. 

